OMG, my son is the math hero in his third grade class. Full of tricks like multiply times eleven - any number. Simply do this... 11 x 35: Take the 3 and the 5 and separate them, add 3+5=8 Put the 8 in between the 3 and 5. 11x35 is 385.  Another example 11 x 72, separate the 7 and 2. 7+2 = 9. Put the 9 between the 7 and 2 and 11 x 72 = 792. Presto. Your kid is a math genius. The book is full of these.