Ruler addition/subtraction
In this example, we are adding 4 + 3 to get 7. Place two rulers next to each other so the top ruler’s end is lined up with the first number in the equation, as below. Move your finger along the top ruler to match the second number in the equation. Then move your finger down from that point. The number on the ruler below will be the answer to the equation.
4 + 3 = 7
Fractions to decimals
Use the following saying to help you remember where to place the numerator and denominator in changing fractions to decimals.
Numerator Nancy goes in the house, but Denominator Dog stays outside.
Denominator Dog 
Numerator Nancy
Long division
Use the following saying to help you remember where to place the numerator and denominator in problems of long division.
Put the “toppings” and the “leftovers” in the refrigerator.
Examples:
12
3
12 is the “topping” because it’s on top,
so it goes in the refrigerator 3 12
262 ÷ 6
262 is the “leftover” number because it’s on the left
so it goes in the refrigerator 6 262