Whole Part Missing number

250

120

?

If we know one part we
can find the other part!

Take the whole, and get rid
of the part you know.

Whatever is left, is the
other part!

250-120= 130

The missing part is 130!

In addition we put the parts together to make the whole!

Part + Part = Whole

In subtraction, we know the whole and are taking away one part

Whole - part = part

So… We always take the whole and subtract the part we know! We are left with the other part

420- ?= 120 I solve this by…. Taking my whole 420 subtract the part I know 120

420-120 = 300
The ? is 300!

Same with addition! I take the whole subtract one part and get the other part!

40 + ?= 90 The whole here is 90. The part I know is 40, so I subtract the part from the whole

90-40= 50

The ? is 50!

Poll

In these type of questions what did you notice?

• We were always subtracting

• we were always adding