# Create new Column in Dataframe with Modulo of other Column

## Question:

I would like to create a new column "Day2" which takes the second digit of column named "Days", so if we have Days equal to 35, we would take the number 5 to be in "Day2", I tried this but it’s not working:

```
DF["Day2"] = DF["Days"].where(
DF["Days"] < 10,
(DF["Days"] / 10 % 10).astype(int),
)
```

It seems it’s taking the first digit but never the second one, can someone help?

## Answers:

I tried this myself and came up with a very simple solution:

```
import pandas as pd
data = [10,11,35,45,65]
df = pd.DataFrame(data, columns=['Day1'])
df['Day2'] = df['Day1'] % 10
df
```

Result

```
Day1 Day2
0 10 0
1 11 1
2 35 5
3 45 5
4 65 5
```

Following your approach you can also do:

```
df['Day2'] = [df["Day1"].where(
df["Day1"] < 10,
(df["Day1"] % 10).astype(int),
)
```

You need to remove the / 10. It always gives you the decimal numbers which divided by % 10 always gives back the very same decimal number since it is always smaller than 10.

Update:

```
df['Day2'] = df["Day1"].mod(10)
```

Yields the same and more pythonic result.