Curriculum Python for Loops and range() for KidsBuilding up a total

How to Build a Running Total with a Python for Loop

Carrying a value forward, loop pass after loop pass.

Lesson 3 of 5PROAges 10+

Building up a total

So far your loops repeated something. Now let's make a loop that BUILDS something up, one pass at a time.

gold = gold + 10, written INSIDE a loop, adds 10 every single time it runs.

gold = 0
for i in range(3):
    gold = gold + 10
    print(gold)

Output

10
20
30

Each pass starts from wherever the LAST pass left off. That's the whole trick — the value carries forward.

gold = 0
for i in range(3):
    gold = gold + 10
    print(gold)

If you only want the FINAL total, move print() outside the loop — so it runs once, after all the passes finish.

gold = 0
for i in range(3):
    gold = gold + 10
print(gold)

Output

Notice the indent difference. Inside the loop = every pass. Outside the loop = just once, at the end.

Check your understanding

gold = 0. This loop runs 3 times, adding 10 each time. Where does print(gold) go to show ONLY the final total?

gold = 0
for i in range(3):
    gold = gold + 10
    ???

Outside the loop, not indented
Inside the loop, same as the line above it
It doesn't matter — indentation doesn't change what happens

Why: Indented under the for, a line runs every pass. Un-indented, back at the loop's own level, it runs once — after the loop is completely finished. That's how you get one final number instead of three.

What you'll practice

The dragon finds 10 gold coins on each of 3 trips. Keep a running total and print the total after each trip — not just the final number.

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Building up a total

Check your understanding

What you'll practice

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