Convert to the Same Kind: Unit Conversion

Methods in this video

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1. 1

   Different units? Convert first

   ▶ 0:41

   When to use it: The same kind of quantity appears in two units (g and kg, mm and cm, mL and L, weeks and years) and has to be added, subtracted or compared, or one amount is written in two parts (8 km 23 m, 1 L 75 mL). The other unit may hide in the last sentence, on a graph's axis, or only in the options.

   • Before you calculate, ask: are these all the same unit? If not, convert first.
   • The smallest unit is the safest: no decimals and no borrowing.
   • Turn a two-part amount into one number and fill the gaps with zeros: 1 L 75 mL is 1075 mL.
   • The other unit may hide in the last sentence or on the axis. When you finish, check which unit the question wants.
2. 2

   Line up the units, multiply down the ladder

   ▶ 4:46

   When to use it: The question asks how many small units are in one big unit (or in several), with at least one unit in between. The links are given (4 gills = 1 pint, 4 azzes in 1 bayo), or you must remember them yourself (days, hours, minutes, seconds).

   • List the units from big to small like a ladder, and write how many small units are in one big unit between each pair.
   • Turn any link that runs the other way around: if a pint is half a quart, then 1 quart = 2 pints.
   • Multiply one rung at a time, stop only at the unit the question asks for, and never add.