DECIMAL NUMBERS

Source: Dev.to

Decimal – Simple Definition

A decimal number is a number written using the base‑10 system.

To break a decimal number (e.g., 2345) into its digits:

• no % 10 → gets the last digit
• no // 10 → removes the last digit

These operations form the core logic used in many programs.

Sum of Digits

Loop Method

no = 2345
sum = 0
while no > 0:
    sum = sum + no % 10
    no = no // 10
print(sum)

Output:

14

Recursion Method

def sum_digits(no, total):
    if no > 0:
        total = total + no % 10
        no = no // 10
        return sum_digits(no, total)
    return total

print(sum_digits(1234, 0))

Output:

10

Count of Digits

Loop Method

no = 2345
count = 0
while no > 0:
    count += 1
    no = no // 10
print(count)

Output:

4

Recursion Method

def count_digits(no, cnt):
    if no > 0:
        cnt += 1
        no = no // 10
        return count_digits(no, cnt)
    return cnt

print(count_digits(123437, 0))

Output:

6

Reverse Number

Loop Method

no = 2345
reverse = 0
while no > 0:
    reverse = reverse * 10 + no % 10
    no = no // 10
print(reverse)

Output:

5432

Recursion Method

def reverse_number(no, rev):
    if no > 0:
        rev = rev * 10 + no % 10
        no = no // 10
        return reverse_number(no, rev)
    return rev

print(reverse_number(123437, 0))

Output:

734321