Complete the Subtraction Sentence - Up to 20
❓ Two types of missing numbers! In subtraction, finding the missing number changes depending on WHERE the missing number is. Let's learn the rules.
Do this: Read the concept below, then try the quiz or activity.
Concept
Missing numbers in subtraction are tricky because there are two different rules!
🎯 Rule 1: The Missing WHOLE (The First Number) ___ - 6 = 10 If the FIRST number is missing, that is the biggest number in the sentence. It's the "Whole" number! To find the big number, you have to ADD the two parts together. * 10 + 6 = 16. * So, 16 - 6 = 10.
🎯 Rule 2: The Missing PART (The Middle Number) 18 - ___ = 12 If the MIDDLE number is missing, you already have the big number (18), and you have a small part (12). To find the other small part, you just SUBTRACT the part you know from the big number! * 18 - 12 = 6. * So, 18 - 6 = 12.
Try it
Pay attention to where the blank is!
Instructions: Does the blank come first (Add) or second (Subtract)?
Problem 1: ___ - 5 = 11 * The first number is missing! We need the BIG number. Add them! * 11 + 5 = ___ * Answer: ___
Problem 2: 17 - ___ = 9 * The middle number is missing. We need a small part. Subtract! * 17 - 9 = ___ * Answer: ___
Problem 3: 15 - ___ = 10 * Answer: ___
Problem 4: ___ - 8 = 12 * Answer: ___