Question

Look at this series: 80, 10, 70, 15, 60, … What number should come next?

Answer 1

Answer:

20

Explanation:

This is an alternating addition and subtraction series. In the first pattern, 10 is subtracted from each number to arrive at the next. In the second, 5 is added to each number to arrive at the next.

$\leadsto$ So, in this way, we reach out to 20 after 60.

The series is something like this :-

80, 10, 70, 15, 60, 20, 50, 25,.......

Answer 2

Explanation:

Given -

80, 10, 70, 15, 60, .......

To Find -

What number should come next ?

As we see :-

First number = 80

second number = 10

Third number = 70

Forth number = 15

Fifth number = 60

Here we see that

After Subtracting 10 in first number, we get third number

It means,

First number - 10 = Third number

• 80 - 10 = 70

Similarly,

After adding 5 in second number, we get forth number

It means,

Second number + 5 = Forth number

• 10 + 5 = 15

Similarly,

After Subtracting 10 in third number, we get fifth number

It means,

Third number - 10 = fifth number

• 70 - 10 = 60

And

Similarly,

After adding 5 in forth number, we get sixth number

It means,

forth number + 5 = sixth number

• 15 + 5 = 20

Hence,

20 comes next in the series.