To multiply double digits less than 100 times any single digit:
-Multiply the single digit multiplier times the ones digit of the double digits. Write this leaving a space between the digits.
-Add the written digits and insert this figure between the written digits. This is the answer.
Examples:
33 X 8 =2_4 , 2 + 4=6 , answer is 264
66 X 3 =1_8 , 1 + 8=9 , answer is 198