Two-digit adding and taking away · Usually met around P1
Two-digit adding, no carrying
Tens with tens, ones with ones.
How to do it
Method
Tens with tens, ones with ones
34 + 25: 3 + 2 = 5 tens, 4 + 5 = 9 ones → 59
Another way
Tens first
34 + 20 = 54, 54 + 5 = 59
In full
A two-digit number is made of tens and ones: 34 is 3 tens and 4 ones. To add, put tens with tens and ones with ones: 34 + 25, tens 3 + 2 = 5 tens, ones 4 + 5 = 9 ones, together 59. Adding a whole ten changes only the tens: 34 + 20 = 54; adding a one-digit number changes only the ones: 34 + 5 = 39. Or add the tens first, then the ones: 34 + 20 = 54, 54 + 5 = 59. You can also lay it out in rods and cubes: count the rods together and the cubes together.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
60 + 39: tens with tens make □ tens, ones with ones make □ ones, so the answer is □.
Fill in each box
Show the answer and working
Answer: 9，9，99
6 + 3 = 9 tens, 0 + 9 = 9 ones, together 99.
Example 2
32 + 67 = □
Show the answer and working
Answer: 99
Tens with tens: 3 + 6; ones with ones: 2 + 7. The answer is 99.
Example 3
70 + 13 = 84
True or false?
Show the answer and working
Answer: False
Tens with tens, ones with ones: 70 + 13 = 83.
Practise it in the game →Two-digit adding and taking away · Free to start, unlimited questions, no download