Happy Valentine’s Week from Mathnasium of Huntington Beach. To celebrate this time we wanted to give you an easy way to add numbers that are close to 10, 100, 1000, etc.
Have you noticed your student struggling with adding 9 to any whole number? Well here is a quick trick. First, you should add 10 to that number and then subtract 1. Let’s look at an example so we can be more clear with what this means. Let’s say your student is asked to add 47 and 9 together. Following the steps mentioned above, first solve 47 + 10, which is 57. Then do 57 - 1, which is 56. Congratulations, you are able to add 47 + 9 to get 56!
We can use this same trick with adding 99 as well, but use 100 instead of 10. An example of this would be 173 + 99. First add 100, so 173 + 100 = 273, then subtract 1. So 273 - 1 is 272. Now we can conclude that 173 + 99 = 272.
You can use this trick with adding any number that consists of 9 in all place values. But what if we wanted to add 8 to numbers? We can do the same addition by 10 trick, but this time subtract 2 instead since 8 + 2 = 10.
Let’s look at another example. Your student has been given the problem 65 + 8. Well first add 10, so 65 + 10 = 75, now subtract 2. 75 - 2 is 73, so 65 + 8 is 73. We can do the same trick for adding 98 as well, just remember to first add by 100, then subtract 2 and you will have the correct answer every time!
Enroll your student here at Mathnasium of Huntington Beach to see what other tricks they can learn to make math more comprehensible.
Phone: (657)203-2304
Email: [email protected]
(657) 203-2304
