Multiplying Large Numbers (Traditional Method) Created by: Sabrina Edmondson Adapted from BBC online

Multiplying Large Numbers If this method seems familiar it might be because you were encouraged to use it in school. Talking through the method is far easier than trying to follow written instructions.

Multiplying Large Numbers Have a look at how the equation 235 x 5 can be worked out using this method. Step 1: 5 x 5 = 25. Put the 5 in the units column, and carry the 2 to the tens. H T O 2 3 5 x

Multiplying Large Numbers Step 2: 3 x 5 = 15. Add the 2 makes 17. 7 goes into the ten’s column and carry the 1 to the hundred’s column. H T O 1 2 3 5 x 7

Multiplying Large Numbers Th H T O 1 2 3 5 x 1 1 7 Step 3: 5 x 2 = 10. Add the carried 1 makes 11. So: 235 x 5 = 1,175

Multiplying Large Numbers Remember to line up the ones, tens and hundreds underneath each other.

Multiplying Large Numbers Now have a look at the equation: 255 x 25 H T O 2 5 x

Multiplying Large Numbers First, multiply 255 by the unit digit 5. Step 1: 5 x 5 = 25. Put the 5 in the units column, and carry the 2 to the tens H T O 2 5 x

Multiplying Large Numbers Step 2: 5 x 5 = 25. Add the 2 makes 27. 7 goes into the tens column and carry the 2 to the hundred’s column. H T O 2 5 x 7

Multiplying Large Numbers Step 3: 5 x 2 = 10. Add the carried 2 makes 12. Th H T O 2 5 x 1 2 7

Multiplying Large Numbers Then multiply 255 by the ten’s digit 2. Remember to place a zero in the ones column first when multiplying the tens. Th H T O 2 5 x 1 2 7

Multiplying Large Numbers Th H T O 1 2 5 x 1 2 7 Step 1: 2 x 5 = 10. Put the 0 in the ten’s column, and carry the 1 to the hundreds.

Multiplying Large Numbers Step 2: 2 x 5 = 10. Add the carried 1 makes 11. 1 goes into the hundred’s column, with 1 carried to the thousands. Th H T O 1 2 5 x 1 2 7

Multiplying Large Numbers Step 3: 2 x 2 = 4, add the carried 1 makes 5. The total is 5,100. Th H T O 1 2 5 x 1 2 7 5 1

Multiplying Large Numbers Finally, add down the columns down to get the total. Th H T O 1 2 5 x 1 2 7 5 1 6 3 So: 255 x 25 = 6,375

Multiplying Large Numbers Remember: Keep the numbers in columns - ones, tens, hundreds etc.  When multiplying the tens digit add a zero to the ones column first.