# Maths Trick 1

**STEP 1**

Ask a friend to write down a number (any number with
more than 3 digits will do, but to save time and effort
you might suggest a maximum of 8 digits).

*Example: 83
972 105*

**STEP 2**

Ask them to add the digits.

*Example: 8+3+9+7+2+1+0+5
= 35*

**STEP 3**

Ask them to subtract this number from the original one.

*Example:
83 972 105 – 35 = 83 972 070*

**STEP 4**

Ask them to select any digit from this new number and strike
it out, without showing you.

*Example: 83
97 2 070*

**STEP 5**

Ask them to add the remaining digits and write down the
answer they get.

*Example: 8+3+9+7+0+7+0
= 34*

**STEP 6**

Ask them to tell you the number they get *(34)* and you will
tell them which number they struck out.

**SOLUTION**

The way you do this is to subtract the number they give
you from the next multiple of 9. The answer you get is
the number they struck out.

*Example: The
next multiple of 9 here is 36 (9 x 4 =36)
36 – 34 = 2 and there you have your answer,
easy isn’t it!*

Note: If the number they give you after step 5 is a multiple of 9, there are two possible answers then you simply tell them that this time they crossed out either a 9 or a zero.

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