To  multiply  a  number  between  10  and  20  by  a  1-digit  number,  multiply  the  1-digit  number  by  10,  then  multiply  it  by  the  second  digit in the 2-digit number, and add the products. Example: 13 × 6 ĺ (6 × 10) + (6 × 3) = 60 + 18; answer: 78


To multiply two numbers that are both between 10 and 20, add the ¿  rst  number  and  the  last  digit  of  the  second  number,  multiply  the  result by 10, then add that result to the product of the last digits in both numbers of the original problem. Example: 13 × 14 ĺ 13 + 4 = 17, 17 × 10 = 170, 3 × 4 = 12, 170 + 12 = 182; answer: 182.