What are you like at multiplications? Chances are if you're a mere mortal 2, 5s and 10s won't seem too taxing. But when it comes to figuring out what 42x21 is, you may wish somebody had shown you the ...

Japanese multiplication step one The blue line represents one ten and the three lines represent three ones. Now, draw the lines for the second number, in this case, the number 21. Again this should be ...