Every teen number holds a ten. 14 is 10 and 4.
Step 1: Let's Learn
Read it, or press Listen and follow the words.
Take from the ten
For 14 − 8, the 4 is too small to take 8 from. So take the 8 from the ten instead.
10 − 8 = 2. Then put back the 4 that was waiting. 2 + 4 = 6.
Why it works
You never lost anything. You only chose which part to take from.
Step 2: Try It Yourself
Tap and try it out.
How many
10 and 4 make 14.
14Whole
10Part
4Part (find it)
10 and 4 make 14.
Take 10 from 14 and 4 is left.
The ten
14 beads moved across in total.
14 beads moved across in total.
How many
10 and 4 make 14.
Step 3: In Real Life
Paying with a ten-dollar bill
A comic costs 6 dollars. You have a ten and 3 ones. Pay from the ten. 4 back, plus your 3. 7 dollars left.
Step 4: Watch an Example
One step at a time.
Watch Leo Take From Ten
Leo is asked for 15 − 9.
- Step 1
He splits 15 into 10 and 5.
Step 5: Your Turn
Practice makes it stick.
Sharing Stickers
Problem 1 of 2
Ana had 13 stickers and gave away 8. How many stickers does she have left?
stickers
The Bus Stop
Problem 2 of 2
16 children were on the bus. 7 got off. How many children stayed on?
children
Take It From the Ten
Split the teen number first.
1 of 4
12 − 9 = ?
2 of 4
14 − 8 = ?
3 of 4
17 − 9 = ?
4 of 4
13 − 7 = ?
Slide the Beads
Build it, then check.
Slide 14 beads across.
0 beads moved across in total.
0 beads moved across in total.
How many
Step 6: Quick Check
Show what you know.
Question 1 of 2
15 − 8 = ?
Question 2 of 2
Why take from the ten in 14 − 9?
What You Learned
- Every teen number holds a ten.
- If the ones are too few, subtract from the ten.
- Then add the leftover ones back on.
For the grown-up
This lesson is where the child subtracts within 20 by taking the subtrahend from the ten inside a teen number. Fluency within twenty is not speed for its own sake. Facts that come without thinking free up the working memory that the next four years of mathematics need, and a child recomputing 8 + 6 every time has nothing left over for the problem it sits inside.
Watch for finger counting that has gone underground — a pause, a glance away, lips moving. The strategy has not gone; it has just got quieter.
Short and often beats long and rare. Two minutes of the facts they nearly know is worth more than twenty minutes of the ones they already do.
The idea behind taking from ten — Every teen number is a ten plus some ones: 14 is 10 and 4, 16 is 10 and 6. When you subtract a number bigger than the ones, the ones alone are not enough. So take the whole amount out of the ten instead, then add the ones back on.
A worked case: 14 - 6 — Step 1: split 14 into 10 and 4. Step 2: take 6 from the 10, leaving 4. Step 3: add back the 4 that was set aside: 4 + 4 = 8. So 14 - 6 = 8. Notice the last step is a double — the strategies keep helping each other.
When to reach for it — Use this when the number you are subtracting is bigger than the ones digit, like 15 - 8 or 13 - 9. When the ones digit is big enough — 17 - 4, say — do not bother; just take 4 from the 7. Part of getting good at math is knowing when a strategy is not needed.
Take it out of the ten — 15 − 8. Fifteen is one ten and five. There are not enough ones, so do not touch them. Take the eight from the ten: 10 − 8 = 2 Put the five back: 2 + 5 = 7 15 − 8 = 7