Using an 'adding on' strategy to find the difference

Maths

If I have £1 to spend in a shop and I spend 47p- how much change will I receive?

If I have £1 to spend in a shop and I spend 68p- how much change will I receive?

If I have £5 to spend in a shop and I spend £3 and 22p- how much change will I receive?

If I have £5 to spend in a shop and I spend £1 and 91p- how much change will I receive?

If I have £10 to spend in a shop and I spend £7 and 22p- how much change will I receive?

Using round and adjust and mental strategies, 34 + 35 =

Using round and adjust and mental strategies, 42+ 46 =

Using round and adjust and mental strategies, 29 + 28 =

Using round and adjust and mental strategies, 35 + 39=

Using round and adjust and mental strategies, 49 + 47 =