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What is the 33rd digit after the decimal point of 4/11?

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

Step by step

The question

Question: What is the 33rd digit after the decimal point of 4/11?

1 Find the block

40 divided by 11 is 3, and 7 is left.

digit 1 = 40 ÷ 11 = 3, 7 left

We divide 4 by 11 the long way.

Each time we bring down a 0.

4 ÷ 11: bring down a 0 each time

70 divided by 11 is 6, and 4 is left.

4 left: that is where we started.

So the digits repeat from here.

digit 2 = 70 ÷ 11 = 6, 4 left

So 4/11 is 0 point 3 6, and the same 2 digits again and again.

411 = 0.36 36 …

The block is 2 long.

length = 2

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

2 times 16 is 32.

So 16 full blocks take us to the 32nd digit.

33 minus 32 is 1 more.

33 ÷ 2 = 2 × 16 = 32, 33 − 32 = 1

3 Count into the block

Careful!

The 16 only counts full blocks.

The 1 left over gives the place.

Careful: not 16: the number of blocks ✗

1 left means place 1 in the block: 3.

33rd digit = place 1 in the block = 3

4 Check

Let's check by counting on.

A block ends at the 32nd digit.

Then we count on: 3.

The 33rd is 3.

So it is right!

32nd = 6 (end of a block), 33rd = 3 ✓

Let's look back.

First: find the block.

Then: divide.

Then: count into the block.

Last: check.

Answer
33rd digit = place 1 in the block = 3

Your turn

Try this one yourself, then check your answer:

What is the 11th digit after the decimal point of 4/11?
Show the answer
3

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