Adding
Line the numbers up by place value (ones under ones, tens under tens) and add from the right. When a column comes to 10 or more, write the ones digit and carry the tens to the next column.
¹¹ 487 + 365 ───── 852
7 + 5 = 12: write 2, carry 1. 1 + 8 + 6 = 15: write 5, carry 1. 1 + 4 + 3 = 8.
Adding a column
With three or more numbers, look for pairs that make 10 or 100 first. 38 + 47 + 62 is (38 + 62) + 47 = 100 + 47 = 147.
Check it: subtract one number from the answer and you should get the other. 852 − 365 = 487.
AFOQT questions on this: Adding up costs