# How to calculate a mod b in Python?

Is there a modulo function in the Python `math`

library?

Isn't `15 % 4`

, 3? But `15 mod 4`

is 1, right?

Asked by:

**Elise873**| Posted: 06-12-2021

# Answer 1

There's the `%`

sign. It's not just for the remainder, it is the modulo operation.

**John977**| Posted: 07-01-2022

# Answer 2

you can also try `divmod(x, y)`

which returns a tuple `(x // y, x % y)`

**Miranda788**| Posted: 07-01-2022

# Answer 3

```
>>> 15 % 4
3
>>>
```

The modulo gives the remainder after integer division.

Answered by:**Max898**| Posted: 07-01-2022

# Answer 4

`mod = a % b`

This stores the result of `a mod b`

in the variable `mod`

.

And you are right, `15 mod 4`

is 3, which is exactly what python returns:

```
>>> 15 % 4
3
```

`a %= b`

is also valid.

**Daisy861**| Posted: 07-01-2022

# Answer 5

Why don't you use % ?

```
print 4 % 2 # 0
```

Answered by: **Jack105**| Posted: 07-01-2022

# Answer 6

I don't think you're fully grasping modulo. `a % b`

and `a mod b`

are just two different ways to express modulo. In this case, python uses `%`

. No, `15 mod 4`

is not `1`

, `15 % 4 == 15 mod 4 == 3`

.

**Darcy503**| Posted: 07-01-2022

# Answer 7

```
A = [3, 1, 2, 4]
for a in A:
print(a % 2)
```

output:

```
1
1
0
0
```

Answered by: **Eric211**| Posted: 07-01-2022

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