Mental Math
Make a 10 or 100 to subtract mentally.
66-29=
What is 37
Round to the nearest tens.
291-125=
What is 160
653-227=
Use addition to check.
What is 426?
A killer whale weighs 8,356 pounds. A walrus weighs 2,737 pounds. How much more does the killer whale weigh than the walrus?
What is 5,619?
On Saturday, Zachary's sister worked in a garden and planted 24 flowers. On Sunday, she planted 15 flowers. How many more flowers did she plant on Saturday than on Sunday?
Exact; What is 9 flowers?
Make a 10 or 100 to subtract mentally.
360-199=
What is 161
Round to the nearest tens.
789-118=
What is 670
500-130=
Use addition to check.
What is 370?
Sonia wants to make 425 get well cards. So far they have made 165 cards. How many more cards do they need to make?
What is 260?
Micheal cut two pieces of rope. One was 32 inches long, one was 49 inches long. Will he have enough rope for a project that needs 76 inches of rope?
788-299=
What is 489
Round to the nearest tens.
9,024-1,916=
What is 7, 100?
3,485-1297=
Use addition to check.
What is 2,188?
Of the 365 days in a year, it rained on 119 days. How many days did it not rain?
What is 246
Kate practiced her guitar for 24 minutes on Monday and 12 minutes on Friday. About how many more minutes did Kate practice on Monday than on Friday?
Make a 10 or 100 to subtract mentally.
130-89=
What is 41
Round to the nearest tens.
7,072-5,872=
What is 1,200
$3568-$639=
Add to check.
What is $2,929
An artist created a piece of art with 675 round glass beads. here were also 179 beads in the shape of a heart. How many more round beads were there?
What is 496?
There are enough seats for 55 students on the bus. Can 35 boys and 28 girls ride the bus? How many more seats are needed for all the students?
Exact; No, 8 more seats are needed.
Make a 10 or 100 to subtract mentally.
521-499=
What is 22
Estimate. Write which place you rounded to.
6,671-2,119=
Hundreds; 4,600
Tens; 4,550
3,008- 1836=
Use addition to check.
What is 1,172
Anton purchased a bike for $153. He gave the clerk one $100- dollar bill, one $50-dollar bill and one $20- dollar bill. How much change should he receive?
What is $17?
The Littleton Library gets 37 new magazines and 45 new books every week. In 3 weeks,about how many more books than magazines will they receive?
Estimate; What is about 30 magazines?