Balance Addition Equations

Balance addition equations

When two addition expressions have the same value, the blank must make both sides equal. The key idea is to compare the sums on each side and find the missing number that closes the gap.

Method

1. Compute the known part of each side.
2. Compare the totals. If one side is smaller, the blank must add just enough to match the other side.
3. Use addition or subtraction to find the missing number:
   • If the blank is part of a sum, ask: “What number makes this total?”
   • You can also subtract the known addend from the total to find the blank.
4. Check by substituting the number back into the equation and verifying that both sums are equal.

Example idea

If one side shows a complete sum and the other side has a blank, first find the value of the complete sum. Then choose the number that makes the incomplete sum match it.

Quick check

After filling the blank, calculate both sides again. If the results match exactly, the equation is balanced. If not, try a different number or recalculate the known sum carefully.