Mastering Mental Math Techniques

The video tutorial provides math tricks for everyday calculations. It explains how to calculate tips using percentage tricks, such as finding 18% of a bill by calculating 50% of 18. Additionally, it offers a multiplication trick for quickly finding the product of 11 and a two-digit number by splitting the digits and placing their sum in the middle. These tricks aim to simplify mental math for common scenarios.

What is the trick to calculate x% of y?

• Subtract y from x and find the percentage

• Add x and y and divide by 2

• Calculate y% of x instead

• Multiply x and y directly

Tags

CCSS.6.RP.A.3C

How can you simplify calculating an 18% tip on a $50 bill?

• Multiply 18 by 50

• Calculate 18% of 50

• Divide 50 by 18

• Calculate 50% of 18

Tags

CCSS.6.RP.A.3C

What is 50% of 18?

• 6

• 7

• 8

• 9

Tags

CCSS.4.NBT.B.5

How do you find the answer to 11 multiplied by a two-digit number?

• Multiply the digits and add them

• Subtract 11 from the two-digit number

• Split the digits, sum them, and place the sum in the middle

• Add 11 to the two-digit number

Tags

CCSS.4.NBT.B.5

What should you do if the sum of the digits is 10 or greater when using the 11 multiplication trick?

• Carry the one

• Add the digits again

• Subtract 10 from the sum

• Ignore the sum

Tags

CCSS.4.NBT.B.5