When we add 1000 to a 4-digit number, we must increase the digit in the Thousands column by 1.
Here is the number 1623 shown on a Thousands Hundreds Tens Ones abacus.
*Notice how the abacus says units. Units are another word for ones.
When we add 1000 we add an extra number to the Thousands column.
1623 + 1000 = 2623
Example
Add 1000 to:
5028
Answer
We increase the 5 in the Thousands column by 1 to get 6 in that column.
5028 + 1000 = 6028
When we subtract 1000 from a 4-digit number, we must decrease the digit in the Thousands column by 1.
Here is the number 4705 shown on a Thousands Hundreds Tens Ones abacus.
When we subtract 1000 from it, we take away one number from the Thousands column.
4705 - 1000 = 3705
Example 1
Subtract 1000 from:
5097
Answer
We decrease the 5 in the Thousands column by 1 to get 4 in that column.
5097 - 1000 = 4097
Example 2
Subtract 1000 from:
1060
Answer
We decrease the 1 in the Thousands column by 1 to get 0 in that column.
Remember to leave off any zeros on the left hand side of a number.
1060 - 1000 = 0060 = 60