Here is a bank of video lessons to support the most efficient calculation methods in Year 5. However, understanding is deepened when new concepts are learned through using a range different representations and not just the ones in these videos.
Mental strategies x 10, 100, 1000
Mental strategies to find decimals using place value and times table facts
Written methods T1s x T1s
Written methods HT1s x T1s
Written methods with 4 digits
Written methods with remainders as fractions and decimals
Fractions Using division to convert between improper and mixed number fractions