My old tutor made me a colorful times table. Basically color in the colums different colors and memorize it by color. Like you don't know what 4*5 is, you solve it or put it in a calculator and fil out the table. After you fil out the table 20 should be in the 4th row and 5th colum. If you colored the 5th colum blue than 20 would be colored in blue. Each colum should be a different color. And if you are color blind then I am so sorry