Mental math

Question 1

sq rt sign with 4 next to it

rt(4)

Answer 1

4^(1/4) = 2^(2*1/4) = 2^ (1/2) ~1.4

Question 2

If you have to add a bunch of #s like 1+2^2+3^2…9^2, trick

Answer 2

first look at answers and see if unit digit is different, if so, just add up the units

Question 3

16^2

Answer 3

256

Question 4

Trick to divide by 5

Answer 4

Multiply by 10, divide by 2

Question 5

Memorize sq rt 5

Answer 5

2.25

Question 6

5/8

Answer 6

.625

Question 7

5/6

Answer 7

.833

Question 8

7/8

Answer 8

.875

Question 9

.9*2 =

Answer 9

FIRST CHANGE TO FRACTION
9/10*2=1.8

Or think it’s almost 2 but not quite so 1.something

Question 10

Faster calc with odd percent like 7%

Answer 10

Do 10%/2 to get 5%

Then 1%+1%

Question 11

15*6

Answer 11

90

Question 12

235-125 = (do this on paper)

Answer 12

110

Question 13

Subtracting 3-4

Answer 13

-1

Question 14

-10 * 10^2

Answer 14

• 10*3, preserve the negative

Question 15

n^n ends in 1 option

Answer 15

1, 5, or 6

Question 16

n^n ends in only 2 options

Answer 16

4 or 9

Question 17

Careless 19+7

Answer 17

26

Question 18

Careless 9 and a in a problem

Answer 18

A (cap) and straight 9, be careful

Question 19

33^43 ends in what digit. TRICK

Answer 19

Divide by 4, not 3

Question 20

Which fractions let you multiply the 1/x to subsequent fractions?

Answer 20

1/9 –> try 5/9=.115
1/11 –> try 5/11=/095
1/6 –> try 5/6 = .167*5=.833
1/7 –> try 5/7 = .14 *5=.7

Question 21

number divis by 8 if

Answer 21

last 3 digits are

or if you can divide by 2 3 times

Question 22

number divis by 9 if

Answer 22

sum of digits divis by 9, just like 3

Question 23

97/7=

Answer 23

NOT 13!!! IT’S 13.SOMETHING

Question 24

4!

Answer 24

24

Question 25

2 stems looks similar

2 stems look identical

Answer 25

A or B bc likely a trick that your’e not seeing

D or E

Question 26

when you have multiple calculations ex: 3x2x2, avoid careless

Answer 26

do each one separately
3x2 = 6
6x2 = 12

Question 27

careless in division - better to write it out

ex: 78/3

Answer 27

78 / 3 (actually cross out so you don’t put 29 instead of 26)

Question 28

10% of 10,000

1% of 10,000

Answer 28

Remove one 0 so 1,000

Remove 2 0’s so 100