Three-digit adding and taking away · Usually met around P2
Adding three numbers in a chain
Add left to right; a column of 20 or more carries 2.
How to do it
Method
Add left to right; a column of 20 or more carries 2
125 + 38 + 214 = 163 + 214 = 377
Another way
Hundreds, tens, ones apart
300 + 60 + 17 = 377
In full
To add three numbers, work from left to right: 125 + 38 + 214, first 125 + 38 = 163, then 163 + 214 = 377. In columns, line up the ones of all three and add from the ones; when a column makes 10 or more, carry 1 to the next place, and 20 or more carries 2: 7 + 8 + 9 = 24, write 4 and carry 2. Or add the hundreds, tens and ones separately: 100 + 200 = 300, 20 + 30 + 10 = 60, 5 + 8 + 4 = 17, then 300 + 60 + 17 = 377.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
52 + 25 + 44 = □
Show the answer and working
Answer: 121
Left to right: 52 + 25 = 77, 77 + 44 = 121.
Example 2
221 + 213 + 185 = 519
True or false?
Show the answer and working
Answer: False
Step by step: 221 + 213 + 185 = 619. Remember to carry.
Example 3
Use columns: 223 + 257 + 274 = □
Show the answer and working
Answer: 754
The ones make 14: write 4, carry 1; the tens carry too: the answer is 754.
Practise it in the game →Three-digit adding and taking away · Free to start, unlimited questions, no download