Friday, August 03, 2007
THE MISSING NUMBER TRICK.
(a) Ask someone to write on a piece of paper (so you can’t see it) a large number (I suggest 5 digits to start with).
(b) Ask them to rearrange the digits in that number and write it above the first number if it is larger but below it if smaller.
(c) Then tell them to subtract the two numbers (they can use a calculator if they wish).
(d) Ask them to circle any digit in the result except zero.
(e) They can then read out (slowly), all the other digits in random order. And you will tell them what the digit is that they circled.
(f) To find the missing digit, simply add up all the digits that they give you - repeatedly - until a single digit 1 to 9 is obtained. If this value is 9, then the number they circled was 9. Otherwise, add a value to the number until it is 9. This value is the number they circled! e.g. If the digits are 9, 8, 8 and 4, then 9+8+8+4=29, 2+9=11, 1+1=2. 9-2=7. Therefore the number circled was 7.
(b) Ask them to rearrange the digits in that number and write it above the first number if it is larger but below it if smaller.
(c) Then tell them to subtract the two numbers (they can use a calculator if they wish).
(d) Ask them to circle any digit in the result except zero.
(e) They can then read out (slowly), all the other digits in random order. And you will tell them what the digit is that they circled.
(f) To find the missing digit, simply add up all the digits that they give you - repeatedly - until a single digit 1 to 9 is obtained. If this value is 9, then the number they circled was 9. Otherwise, add a value to the number until it is 9. This value is the number they circled! e.g. If the digits are 9, 8, 8 and 4, then 9+8+8+4=29, 2+9=11, 1+1=2. 9-2=7. Therefore the number circled was 7.
// posted by Kritidas @ 2:27 AM 
