
Kristoffer H. answered 02/13/13
Specialize in teaching Access, Excel, SQL, Algebra, Statistics
Most folks CAN do large numbers in their head; the problem is we are not taught it. The easiest method is the one Mel S. just explained. Simply learn to round and add....Round 34 to 30 and multiply that by 8, and your brain will eventually learn how to see (30*8 = 240), + (4*8 = 32) = 272
Let me explain this in a practical sense; years ago it was practical to leave a 15% tip to your waiter. So let’s say you got a bill of $28 for a pizza, and you were to tip them 15%. My method was to simply multiply $28 x .10 (10%) which got me to move the decimal over one space $2.80) now to add the 5%; I cut $2.80 in half which would be $1.40, and added $1.40 to $2.80 which got me $4.20. To me that is simple math but the easiest method just double the tax, round to the highest whole dollar, and leave that as the tip. LOL
Math is much more fun when you find practical applications for it.