Foundation November 2017 Paper 1 Q9

9 Jacqui wants to work out \(3480 \div 5\)

She knows that \(3480 \div 10 = 348\)

Jacqui writes \(3480 \div 5 = 174\)
because \(10 \div 5 = 2\)
and \(348 \div 2 = 174\)

What mistake did Jacqui make in her method? (1)