Mental Math

Place Value

100

How many ones are there in 17

7

200

What number is on the tens place in 239

3

300

I have 3 tens and 0 ones, what number am I?

30

400

I have 4 hundreds, 0 tens, and 8 ones. What number am I?

408

500

4000 + 800+70 +8=?

4878

Rounding

100

Round this number to the nearest 10: 72

70

200

Round this number to the nearest hundred: 312

300

300

Round this number to the nearest thousand: 4102

4000

400

Do we round up for 25 or down?

Up.

500

What is the closest thousand(s) to 4892?

5000

Addition

100

2+1=

3

200

14+3=

17

300

23+12=

35

400

143+20=

163

500

250+148=

398

Subtraction

100

8-3=

5

200

16-4=

12

300

45 - 12 = 

33

400

134 - 30 =

104

500

345 - 124 = 

221

Word Problem

100

Mary has 2 pencils. Riley has 3 pencils. How many pencils do they have together?

5

200

Johnny and Peter own 12 erasers together. Johnny has 6. How many eraser(s) does Peter have?

6

300

Isabelle runs 5 laps a day. How many laps in total will she run in 4 days?

20

400

Emily is saving up for a Nintendo Switch. She can save 50 dollars every month. If a Nintendo Switch is 400 dollars, how many months will she have to save her money?

8

500

Loblaws has a sale going on right now. You can get 2 watermelons for 10 dollars. How much do I have to pay if I would like to buy 8 watermelons?

$40