Common Core maths standard · Grade 1

1.OA.D.8

Find the unknown number in an addition or subtraction equation, and see subtraction as an unknown-addend problem. One game practises it.

Grade 1

Add & subtract within 20 · Tens & ones · Measuring length

1 think & learn

Think & learn 1.OA.D.8 · 1.OA.B.4

What number is hiding? Hop on the number line to find it.