AI Tutor
Imagine you are packing cargo for an airplane with a strict safety limit: the plane can carry exactly 1.5 metric tons of cargo. You have crates labeled in grams, boxes labeled in kilograms, and giant pallets labeled in tons.
If you just add the numbers on the labels without checking the units, the plane might be dangerously overloaded! To solve real-world problems like this, we need a clear plan to convert and calculate step by step.
How do these mass units connect with each other?

The Mass Conversion Bridge

The metric system was established in France in 1795 to make trade simple by using powers of 10. For mass, every major jump between grams (g\text{g}), kilograms (kg\text{kg}), and metric tons (t\text{t}) changes by a factor of 1,0001{,}000.
One kilogram equals 1,000 g1{,}000\text{ g}, and one metric ton equals 1,000 kg1{,}000\text{ kg} (which is 1,000,000 g1{,}000{,}000\text{ g}). Multiply by 1,0001{,}000 to step down to smaller units, and divide by 1,0001{,}000 to step up to larger units.
Now, how do we tackle a word problem that mixes all three units?

Strategy: Unify, Calculate, Convert

Whenever you face a multi-step problem with mixed mass units, always follow three golden steps: first, convert every measurement into one common unit; second, perform the addition or subtraction; third, convert your final answer into the requested unit.
Let's work through an example: A bakery receives a delivery of 0.4 t0.4\text{ t} of flour. On Monday, bakers use 185 kg185\text{ kg}, and on Tuesday, they use 65,000 g65{,}000\text{ g}. How many kilograms of flour remain?
Notice how converting everything to kilograms right away made the arithmetic simple and painless: 400−(185+65)=150 kg400 - (185 + 65) = 150\text{ kg}.