Show The Tens Fact You Used. Write The Difference

The Tens Fact You Used

You’re working through a math problem — maybe helping a kid with homework, maybe brushing up on your own skills — and someone says, “Use a tens fact to solve this.” You nod along, but honestly? What even is a tens fact?

Here’s the thing: tens facts are one of those deceptively simple ideas that become incredibly powerful once you really get them. Now, they’re not just for elementary school. Adults use them all the time without realizing it. And once you see how they work, a whole bunch of arithmetic suddenly gets easier.

So what’s a tens fact? At its core, it’s any addition or subtraction equation where one of the numbers is ten. Now, easy enough. But the real trick isn’t just knowing that 10 + 3 = 13. It’s using that fact strategically to break down harder problems into something you already know.

Why Tens Facts Matter

Most people think math is about memorizing a million separate facts. On the flip side, twenty-three plus seven? That’s its own thing. Eight plus five? Another isolated fact. But the truth is, good mathematicians don’t memorize everything. They look for patterns and relationships.

Tens facts are one of those patterns. When you can quickly recognize that 8 + 5 is really 8 + 2 + 3, and that 8 + 2 makes 10, suddenly 8 + 5 becomes 10 + 3, which is 13. But no memorization required. Just restructuring.

This matters because mental math becomes so much faster when you’re not grinding through every single calculation from scratch. On top of that, it also builds number sense — the intuitive feel for how numbers relate to each other. And that’s useful far beyond the classroom.

How Tens Facts Work

Let’s get concrete. Here’s how you actually use a tens fact to solve a problem.

Breaking Numbers Apart to Make Ten

Take 7 + 6. Most people don’t have that one memorized instantly. But here’s what you do: look at the 6. Can you split it into two parts — one that makes 7 into 10, and the rest?

Seven needs 3 more to make 10. So you take 3 from the 6, leaving 3 behind. Now you’ve got 10 + 3, which is 13.

That’s the tens fact strategy in action: 7 + 6 becomes 10 + 3.

Subtraction Using Tens

Subtraction works the same way, just in reverse. Say you’re solving 15 − 8. Still, you could count backward from 15, but that’s slow. Instead, think: 15 is 10 + 5. So take away 8 from the 10 first. In real terms, that leaves you with 2, and then add back the 5 you set aside. 2 + 5 = 7.

Or, flip it: you know that 8 + 7 = 15 (because of the tens fact trick above). So 15 − 8 must be 7.

Either way, you’re leaning on your comfort with tens to avoid getting stuck.

Working with Larger Numbers

This scales up, too. If you’re adding 48 + 15, you can think of it as 48 + 12 + 3. The 48 + 12 part? That’s another tens fact setup — 48 + 2 makes 50, so 48 + 12 = 60. Then 60 + 3 = 63.

The pattern stays the same. Find the piece that gets you to a multiple of ten, deal with that, then handle the remainder.

Common Mistakes With Tens Facts

Even people who think* they get tens facts mess them up in predictable ways.

Forgetting the Remainder

This is the big one. Someone sees 9 + 6 and thinks, “Okay, 9 needs 1 to make 10, so I’ll take 1 from the 6.On the flip side, ” They write down 10, and then... Because of that, stop. They forget the 5 that’s left over. Answer? Because of that, 10. Wrong by 5.

The fix is simple but easy to overlook: always track both parts. When you split 6 into 1 and 5, you have to account for both.

Overcomplicating Simple Problems

Some people hear “use a tens fact” and try to force every problem into that mold, even when it doesn’t help. Like, 10 + 4 doesn’t need a tens fact strategy. It just is one.

The goal isn’t to use tens facts everywhere. It’s to use them where they actually make things easier.

Mixing Up the Direction

In subtraction, people sometimes take from the wrong number. Because of that, if you’re doing 13 − 5, you might think, “5 needs 8 to make 13. ” That’s true, but it’s not helpful. Instead, think: 13 is 10 + 3. Take 5 from the 10, leaving 5. This leads to add back the 3. That gives you 8.

Subtraction with tens facts works best when you decompose the larger number, not the smaller one.

Practical Tips That Actually Work

Here’s what helps when you’re trying to get fluent with tens facts.

Practice the Bonds First

Before you worry about applying tens facts, make sure you know your “ten bonds” cold. Now, 1 + 9, 2 + 8, 3 + 7, 4 + 6, 5 + 5. These should be instant. No hesitation.

If you’re still counting on your fingers for 7 + 3, the tens fact strategy will feel clunky. Build that foundation first.

Use Visuals When Starting Out

A number bond diagram or a quick sketch of circles can help you see what you’re doing. Circle 2 of the 5 to pair with the 8, making 10. Plus, draw 8 circles and 5 circles. The leftover 3 circles join the 10. Now it’s visual, not abstract.

For more on this topic, read our article on correctly label the components of the upper respiratory tract. or check out classify the following triangle check all that apply 54 36.

Most people outgrow the need for this, but starting with pictures makes the whole thing click faster.

Turn It Into a Game

Seriously. Grab a deck of cards, pull out the face cards, and play “Make Ten.So ” Flip two cards and see if they add up to ten. Or play “Tens Go Fish” — instead of asking for matches, you ask for the number that makes ten with what you’re holding.

Games make the facts stick without feeling like drill-and-kill.

Teach Someone Else

There’s no better way to solidify your own understanding than trying to explain it to someone who doesn’t get it yet. Even so, watch where they get confused. Walk a friend through how 8 + 5 becomes 10 + 3. That’s where you’ll find your own gaps.

FAQ

What’s a tens fact example?
Any equation involving ten counts. 10 + 7 = 17, 10 − 3 = 7, or using 10 as a stepping stone in harder problems like 9 + 6 = 10 + 5 = 15.

How do you use tens facts in subtraction?
Break the larger number into ten and something else. For 14 − 6, think 14 as 10 + 4. Take 6 from the 10, leaving 4. Add back the 4 you set aside. Answer: 8.

Are tens facts the same as doubles?
Nope. Doubles are like 4 + 4 or 7 + 7. Tens facts specifically involve the number ten, either directly or as a strategy for reaching ten.

When should kids learn tens facts?
Usually in first or second grade, after they’re solid on basic addition and subtraction. But the concept sticks around forever — adults just use it without thinking about it.

Can you use tens facts with bigger numbers?
Absolutely. 38 + 17 becomes 38 + 12 + 5, which is 50 + 5 = 55. The principle stays the same no matter how big the numbers get.

Making It Stick

Here’s what I’ve

learned from working with hundreds of students: fluency with tens facts isn’t about memorizing endless lists of equations. It’s about understanding the relationship between numbers and ten.

The key insight? Plus, when you understand that 7 + 3 = 10, you’ve unlocked a tool that works for 27 + 3, 17 + 3, even 0. It’s the bridge that connects what we know to what we’re trying to figure out. Ten is our base number. Worth adding: 27 + 0. 03.

Don’t rush the process. Some kids need weeks with manipulatives. Others click almost immediately. Here's the thing — both are fine. What matters is that they’re building mental models, not just memorizing procedures.

Common Mistakes to Avoid

Parents and teachers often make a few predictable errors here.

Teaching the procedure backwards. You start with the smaller number and try to make it work with the larger one. This creates unnecessary cognitive load. Always decompose the larger number first.

Skipping the bond practice. If students can’t instantly recall that 8 + 2 = 10, asking them to use this in complex problems is like asking someone to run before they can walk.

Over-emphasizing the written method. While pencil-and-paper has its place, tens facts are fundamentally mental math tools. The goal is fluency in your head, not just on paper.

Real-World Applications

This isn’t just academic busywork. Tens facts show up everywhere.

When you’re shopping and see $4.99 items marked down to $3.99, you’re mentally calculating the difference using tens logic. When you split a $28 bill among 4 people, you might think 28 = 20 + 8, then divide each part.

Even estimation relies on this foundation. If you need to add 49 + 38, rounding to 50 + 40 and then subtracting 2 makes perfect sense when you understand how tens facts work.

The Long Game

Here’s what I’ve learned from watching students grow from struggling with 8 + 5 to confidently solving 38 + 25 in their heads: patience and the right foundation matter more than speed.

Fluency with tens facts isn’t a destination; it’s a skill that compounds. On the flip side, each year, students build on this base with hundreds facts, then thousands, then decimals. But if the foundation is shaky, everything built on top wobbles.

The beauty of tens facts is that they’re always relevant. In a world of calculators and computers, the ability to think flexibly about numbers remains uniquely human. It’s the difference between following a procedure and actually understanding what numbers are doing.

So keep practicing. Plus, keep making connections. And remember: every time you break a number apart to make ten, you’re not just solving a problem—you’re building a way of thinking that will serve you for life.

The goal isn’t perfection. Think about it: it’s confidence. When a student looks at 9 + 6 and sees 10 + 5 instead of having to count up, something fundamental has shifted. They’ve discovered that math makes sense.

That moment of recognition—that’s worth more than any grade.