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What is the 25th digit after the decimal point of 1/37?

Step by step, with the reason for every step · ACT: Repeating patterns · ACT Math

Step by step

The question

Question: What is the 25th digit after the decimal point of 1/37?

1 Find the block

10 divided by 37 is 0, and 10 is left.

digit 1 = 10 ÷ 37 = 0, 10 left

We divide 1 by 37 the long way.

Each time we bring down a 0.

1 ÷ 37: bring down a 0 each time

100 divided by 37 is 2, and 26 is left.

digit 2 = 100 ÷ 37 = 2, 26 left

260 divided by 37 is 7, and 1 is left.

1 left: that is where we started.

So the digits repeat from here.

digit 3 = 260 ÷ 37 = 7, 1 left

So 1/37 is 0 point 0 2 7, and the same 3 digits again and again.

137 = 0.027 027 …

The block is 3 long.

length = 3

2 Divide

The block comes again and again.

So we divide by its length.

What is left over tells us the place in the block.

n ÷ (length of the block): what is left = the place in the block

3 times 8 is 24.

So 8 full blocks take us to the 24th digit.

25 minus 24 is 1 more.

25 ÷ 3 = 3 × 8 = 24, 25 − 24 = 1

3 Count into the block

Careful!

The 8 only counts full blocks.

The 1 left over gives the place.

Careful: not 8: the number of blocks ✗

1 left means place 1 in the block: 0.

25th digit = place 1 in the block = 0

4 Check

Let's check by counting on.

A block ends at the 24th digit.

Then we count on: 0.

The 25th is 0.

So it is right!

24th = 7 (end of a block), 25th = 0 ✓

Let's look back.

First: find the block.

Then: divide.

Then: count into the block.

Last: check.

Answer
25th digit = place 1 in the block = 0

Your turn

Try this one yourself, then check your answer:

What is the 22nd digit after the decimal point of 1/37?
Show the answer
0

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