This lesson is the continuation of the first grade multiplication lesson.Multiplication tablesHere are the multiplication 6 times, 7 times, 8 times and 9 times tables. Learn them by heart! When you think you know them well, clik the button "training".
Writing down a multiplication1 - Simple multiplication without carryingWe now will see how to calculate multiplications with large numbers, but only when one of the two numbers is smaller than 10. For instance let us see how to calculate 312 × 3. You multiply the 3 below by the units number, then by the tens number and by the hundreds numbers (on the top). So you start with multiplying 3 by 2. 3 × 2 = 6 so you place a 6 below the line. You multiply 3 by 1. You get 3, so you place it below the line. Next you multiply 3 by 3, you get 9 and so you place a 9 below the line. Now you can read the result : 312 × 3 = 936. 1 - Simple multiplication and carrying When you multiply two numbers, the result is often bigger than 10. In this case, you write below the line only the units number of the result, and you write somewhere on the right of the multiplication the number of tens contained in the result. For example, in the multiplication 258 × 3 : You start with calculating 3 × 8 and you get 24. So you place a 4 below the line and you carry 2 numbers on the right of the multiplication. Then, you do the multiplication and you add the numbers you have just carried. 3 × 5 = 15, 15+2=17, so you have to write 17. Since it is a number larger than 10, you just write the number 7 below the line, you cross out the number previously carried, and you carry another number. Finally you do the last multiplication, 3 × 2 = 6 , adding the number carried you get 7, so you place 7 below the line and you can read the result : 253 × 3 = 774. Attention! To calculate all this you have to know the multiplication tables very well! To train yourself Use this method to answer the following question : What is the result of 921 × 3 ?
Learn more about the multiplication on the website Multiplication 50. You will cross the United States by the road 50. |