Thursday, August 18, 2011

Age and Siblings Math Trick

Ok here's a cool math trick that will give you an answer with your age and the number of siblings you have
1.   Take Your age
2.      Multiply your it by 2                   
3.      Add 10 to the number you got in step 2                                      
4.      Multiply that number by 5                                 
5.      Add # of siblings you have 
6.     Subtract 50     

Monday, August 15, 2011

squaring numbers that end in five

take a number that ends in five lets say 35 and first take the first digit and multiply it by itself +1 so 3x(3+1) and you get 12 so those are the first two digits then take the square of 5 and get 25 so you get 1225.  I Guarantee this works with any number ending in five.

Sunday, August 14, 2011

multiplying two numbers in the 90's (Insane math tricks)

Okay so everyone wants to do multiplication quickly right.  Well we all know how to multiply by 10, 1, 2,3,4,5,6,7,8, and even 9 but what about 90's.  Here is a trick to multiply numbers in the 90's quick and easy.
So take two numbers in the 90's let's say 94 and 97 we type it in on a calculator and get 9118 and here is how you can do it in your head.
1. find the distance from 100 both numbers are. 94 is 6 and 97 is 3
2. add the distances together and you get 9
3. subtract that number from 100 and get 91 a.k.a the first two digits of the answer.
4.Take the two distances from step one and multiply them together and you get 18 a.k.a the last two digits of the number giving you the final answer 9118.
Use this on any other set of two numbers in the 90 to 99 range and i guarantee it will work.

Play Store (for kids)

Parents in first or second grade kids will have to learn how to count money and figure out change which will last throughout all of their lives in story problems. An easy way to make this work is to play store.
1. Take old objects (and new if you choose) and add a price tag to each, depending on what you think they would actually cost.
2. Think through the prices depending on the child's skill level.  For a first grader try using only values that use quarters, 25 cents 50 cents 75 cents one dollar and so on.  For a third grader or older start using less normal numbers. Ending in any number instead of only 5's and 0's.
3. Have your child pick out a set number of items and have them total their purchase.
4. Have them give either exact amount of money or make them use dollar bills only to pay.
5. If they used dollar bills have them tell you how much change they should get.
This is a very fun and easy way to learn cash math for kids.