Key Idea1 of 3
Three Types of Missing Numbers
Type 1: __+3=7 → subtract: 7-3=4. Type 2: 5+__=9 → subtract: 9-5=4. Type 3: __-2=6 → add: 6+2=8. The key is to look at where the blank is and what operation is shown, then use the inverse operation to find the answer.