Explanation:
To add whole numbers or decimals without a calculator, write the numbers in vertical columns with their place values lined up (units under units, tens under tens, and decimal points in a vertical line). If decimals have different lengths, fill any empty spaces at the end with placeholder zeros so every number has the same number of decimal places.
Add each column from right to left. Whenever a column adds up to 10 or more, write down the units digit in the answer row and carry the tens digit underneath the next column to the left. Remember to add any carried digits into the next column.
Example 1: Work out 4786 + 859
Solution:
Units: 6 + 9 = 15 (5, carry 1)
Tens: 8 + 5 + 1 = 14 (4, carry 1)
Hundreds: 7 + 8 + 1 = 16 (6, carry 1)
Thousands: 4 + 1 = 5
Answer: 5645
Example 2: Work out 34.6 + 7.08 + 125.45
Solution:
| | 3 | 4 | . | 6 | 0 |
| | | 7 | . | 0 | 8 |
| + | 1 | 2 | 5 | . | 4 | 5 |
| 1 | 6 | 7 | . | 1 | 3 |
| | 1 | 1 | | 1 | |
Write 34.6 as 34.60 (2 d.p.)
0.01s: 0 + 8 + 5 = 13 (3, carry 1)
0.1s: 6 + 0 + 4 + 1 = 11 (1, carry 1)
Units: 4+7+5+1 = 17 (7, carry 1)
Answer: 167.13