Subtracting from 10 - First Grade Mathematics

Because the number 10 is the anchor of our number system, mastering subtraction facts from 10 is one of the most valuable skills you can acquire. Every time you subtract from 10, you are simply visiting your old friends: the Friends of 10! If you know that 7 and 3 make 10, then you already know that 10 take away 7 leaves 3, and 10 take away 3 leaves 7. In this chapter, you will master all the subtraction facts with a minuend of 10, use ten-frames to visualize removal, and learn to subtract from ten without hesitation.

All the Subtraction Facts from 10

Here is the complete family of subtraction facts starting with 10:

The Subtraction Table from 10:
10 - 0 = 10          10 - 6 = 4
10 - 1 = 9           10 - 7 = 3
10 - 2 = 8           10 - 8 = 2
10 - 3 = 7           10 - 9 = 1
10 - 4 = 6           10 - 10 = 0
10 - 5 = 5

The Symmetrical Pairs

Notice how the answers mirror each other: 10 - 8 = 2 and 10 - 2 = 8 10 - 7 = 3 and 10 - 3 = 7 10 - 6 = 4 and 10 - 4 = 6 10 - 9 = 1 and 10 - 1 = 9 Because 8 and 2 are partners that make 10, subtracting either partner always leaves the other!

Seeing Subtraction on a Ten-Frame

A full ten-frame has 10 counters. To subtract, remove counters and count what remains.

Solving 10 - 4 on a Ten-Frame:
Step 1: Start with a FULL frame of 10:
+---+---+---+---+---+
| * | * | * | * | * |
+---+---+---+---+---+
| * | * | * | * | * |
+---+---+---+---+---+

Step 2: Cross out 4 counters from the bottom:
+---+---+---+---+---+
| * | * | * | * | * |  -> Top row full (5)
+---+---+---+---+---+
| * | X | X | X | X |  -> 1 counter left on bottom
+---+---+---+---+---+

What is left? 5 on top + 1 on bottom = 6 counters!
10 - 4 = 6!

The Instant Five Anchor

Notice how easy it is to count what is left: the top row is completely untouched, so you immediately have 5. Just add whatever is left on the bottom!

Using Fingers to Subtract from 10

Your hands are an instant set of 10 counters.

Finger Subtraction from 10:
Hold up all 10 fingers.
Problem: 10 - 7
Fold down 7 fingers (5 on one hand, 2 on the other).
How many fingers are still standing? 3 fingers!
10 - 7 = 3!

Practice Exercises

Exercise 1: Solve each of these subtraction equations from 10: 10 - 3 = __ 10 - 8 = __ 10 - 5 = __ 10 - 1 = __

Exercise 2: You have a ten-frame completely full of pennies. You take 6 pennies out to buy a sticker. How many pennies remain in the ten-frame?

Exercise 3: Explain how knowing the addition fact 2 + 8 = 10 helps you solve the subtraction problem 10 - 8.

Exercise 4: Write all the related subtraction equations that can be formed using the numbers 4, 6, and 10.

Solutions and Explanations

Solution to Exercise 1: 10 - 3 = 7 10 - 8 = 2 10 - 5 = 5 10 - 1 = 9

Solution to Exercise 2: There are 4 pennies remaining in the ten-frame (10 - 6 = 4).

Solution to Exercise 3: Knowing that 2 and 8 are parts that join to make the whole of 10 means that if you start with the whole of 10 and take away the part of 8, the other part (2) must be what is left over.

Solution to Exercise 4: The two subtraction equations are 10 - 4 = 6 and 10 - 6 = 4.