100.
(a) 1 metre = ____ millimetres.
(b) 1 centimetre = ____ millimetres.
(c) 1 kilometre = ____ millimetres.
(a) 1000 mm
(b) 10 mm
(c) 1,000,000 mm
(a) Convert metre → centimetre → millimetre.
Step 1: \(1\,\text{m} = 100\,\text{cm}\).
Step 2: \(1\,\text{cm} = 10\,\text{mm}\).
Step 3: \(100\,\text{cm} = 100 \times 10\,\text{mm}\).
So, \(100\,\text{cm} = 1000\,\text{mm}\).
Therefore, \(1\,\text{m} = 1000\,\text{mm}\).
(b) Centimetre to millimetre.
By definition: \(1\,\text{cm} = 10\,\text{mm}\).
(c) Convert kilometre → metre → millimetre.
Step 1: \(1\,\text{km} = 1000\,\text{m}\).
Step 2: From part (a), \(1\,\text{m} = 1000\,\text{mm}\).
Step 3: \(1000\,\text{m} = 1000 \times 1000\,\text{mm}\).
\(1000 \times 1000 = 1{,}000{,}000\).
So, \(1\,\text{km} = 1{,}000{,}000\,\text{mm}\).