The star map gets more precise

Liri’s star map was divided into little squares – like a grid over the whole universe. Every memory she had was a number of squares in a particular direction.

Liri: “I remember: I flew 356 squares past a nebula. Then another 274 squares past a comet trail. If I add that up, I’ll know exactly how far I am from home.”
Erklärus: “Those are numbers that are too big for your head alone. But that is exactly what column addition is for – working one under the other, place by place. That way you lose nothing, and you don’t need any extra paper.”
Liri: “Then let’s make my map more precise.”

✍️ Why work in columns?

With small numbers your head is enough. But with three-digit numbers it quickly becomes confusing. That is why you write the numbers one under the other – ones under ones, tens under tens, hundreds under hundreds – and work from right to left, column by column.

If a column adds up to more than 9, you write down only the ones digit and pass the rest on to the next column as a carry.

🔍 An example – step by step

Click on a digit to see what happens:

1
1
3
5
6
+
2
7
4
6
3
0
← Click on a digit!
Liri: “356 + 274 = 630 squares. Now I know exactly where this point is on my map!”

📝 Now you – fill in the place values yourself

Liri remembers another stretch of the route: 418 squares past a comet, then 356 squares past a cloud of stars. Work it out in columns – write your carry and your answer right here:

HTO
4
1
8
+
3
5
6

📝 Another stretch – this time with two carries

The next section: 467 squares and 258 squares. Watch out – there are two carries here!

HTO
4
6
7
+
2
5
8

✨ Bonus puzzle – the round number

Liri has noticed something special: if she adds exactly 526 squares and 474 squares, she lands on a particularly important, round point on her map – exactly 1,000! Check it:

ThHTO
5
2
6
+
4
7
4
🌌 Big numbers in the universe

A year on Mars lasts 687 Earth days – almost twice as long as a year on Earth.
Without column calculation, scientists couldn’t add up such big numbers reliably – a single forgotten carry, and the whole journey would be calculated wrongly.

❌ Common mistake

The most common mistake in column addition: forgetting the carry.

Example: 356 + 274 → ones: 6+4=10 → write 0, carry 1. Anyone who forgets the 1 goes on to get the tens place wrong.

Tip: always write the carry small above the next column before you carry on!

A point on the map

Liri drew a little golden dot on her star map. With every calculation it became more precise.

Liri: “630 squares. 725 squares. And now even exactly 1,000 at this round point. My map is getting more and more precise.”
Erklärus: “That is the lovely thing about column addition. It doesn’t forgive carelessness – but it rewards patience with accuracy.”
“Column addition: write the numbers one under the other, place by place from the right. Note the carry small above the next column. That is how single memories become exact coordinates.”
What you learned today
356 + 274 = 630
In columns: start on the right · place by place · don’t forget the carry
🌟

Chapter 14 mastered!

Liri’s star map is more precise than ever – thanks to column addition up to 1,000.

Erklärus’s notebook – page 14:
“Column addition: write one under the other, from right to left, place by place. Note the carry, don’t forget it. Liri added three stretches of the route: 630, 725 and – at the round point – exactly 1,000 squares.”
← Back to overview 14 – Column Addition