Multiplication of OneDigit by TwoDigit NumbersPreparation This will be a preparation for problems such as 5 x 10, 10 x 5, 3 x 20, and 20 x 3. Method 1: For problems such as 5 x 10, whenever a number is being multiplied by ten, that number simply gets a zero written on to the end of it. This is the same as increasing the place value of that number. So, 5 x 10 = 50.
Method 1: For a problem such as 3 x 32 split the 2digit number into ones and tens and multiply each by the 1digit number. Then add the results to get the product. Practice these problems using method 1: Practice 2: Method 2: For problems such as 12 x 3, use the Commutative Property to switch the numbers and solve using Method 1. Solve Mentally: 
