Give a friend a calculator and tell them to key in the number of the month in which they were born.
- Multiply by 4
- Add 13
- Multiply by 25
- Subtract 200
- Add the day of the month they were born
- Multiply by 2
- Subtract 40
- Multiply by 50
- Add the last two digits of the year they were born
- Subtract 10,500
Ask to look at the calculator and then tell them their full date of birth. The first one or two digits gives the month, the next two gives the day, the last two gives the year.
This is just one trick you'll find in Johnny Ball's Go Figure! A Totally Cool Book About Numbers. Whether you absolutely love math or hate it, you won't be able to resist this intriguing book all about numbers. It is bursting with mind boggling brain teasers, magic, illusions and puzzles that are both challenging and fun. You'll also see that numbers relate to practically everything around us whether it is history, art, science, music, magic, sports or the lottery!