The Big Ten Trick
Sam has 25 rocks. Sam gets 10 more! Can you help Sam add fast?
1st Grade MathStep 1: Look at the Tens
25 has tens and ones. How many big tens boxes can you see?
25 has 2 tens and 5 ones. The 2 in 25 tells us the tens.
Step 2: Add 1 Ten
Sam gets 10 more rocks! We add 1 new ten. It is the last big box.
25 + 10 = ?
2 tens + 1 ten = 3 tens. The ones stay the same. So 25 + 10 = 35.
The Big Ten Trick
Add or Subtract 10
Add 10: the tens go up by 1.
Subtract 10: the tens go down by 1.
The ones stay the same!
Subtract 10: the tens go down by 1.
The ones stay the same!
Sam
No need to count! Just fix the tens. So fast!
Add 10!
43 + 10 = ?
The tens go up by 1.
4 tens + 1 ten = 5 tens. The 3 ones stay. So 43 + 10 = 53.
Subtract 10!
Now we subtract. Take 1 ten off!
67 - 10 = ?
Take 1 ten from 6 tens. That is 5 tens. So 67 - 10 = 57.
Help Meg!
Meg has 52 shells. Kit takes 10 of them.
How many shells are left?
52 - 10 = 42. 5 tens go down to 4 tens. The 2 ones stay.
What is Missing?
? + 10 = 89
What did we start with?
79 + 10 = 89. The tens go up by 1: 7 tens to 8 tens.
Help Fox!
Fox has 81 figs. Fox eats 10 figs.
How many figs are left?
81 - 10 = 71. 8 tens go down to 7 tens. The 1 one stays.
Big Task!
Dot hops from 47. She adds 10, then 10 more.
Where will Dot stop?
47 + 10 = 57. Then 57 + 10 = 67. Two hops of ten!
Think!
When would you add 10 in real life? Tell a grown-up!
You Did It!
0/8
correct
add
subtract
tens
ones