Gmat Fdp 1: Digits And Decimals Strategy

Front 1

If A has two digits, what is the algebraic equation for A's digits?

Back 1

A = 10x + y

Front 2

Explain the "last digit shortcut."

Back 2

When asked for the last digit of a group of numbers being summed or multiplied together, just handle the ones digit of all the numbers and sum/multiply them together.

This works because the final ones digit is the sum/product of the ones digits of all the terms.

Front 3

Explain the "heavy division shortcut."

Back 3

1) Move decimal point for both numbers being divided to the left until the denominator has 1 digit left.
2) Round both numbers to whole numbers.
3) Divide

Note: If more precision is needed, just bring back one digit for each number and then divide.

Front 4

(0.5)^4= ?

Back 4

1) Rewrite as (5 * 10^(-1)) ^ 4
2) 5^4 * 10^(-4)
3) 625 * 10^(-4)
4) .0625 [shift left using 10^(-4) ]

Front 5

3 square root(.000027) = ?

Back 5

divide the number of places by the value of the root (multiply if it's a power)

Answer = .03

Front 6

How many decimal places does (.04)^3 have?

Back 6

2 decimal places * 3 exponent = 6 decimal places.

.000064

Front 7

How many decimal places does
3 square root (.000000008) have?

Back 7

9 places / 3 root = 3 places

.002