: Advanced addition, subtraction, multiplication, and division.
You can find step-by-step solutions for each page of the 2015/2016 edition on popular educational sites: gdz po matimatike za 5 klass 1 chast kozlova rubin
If you are struggling with a specific concept, these are the main areas covered in the first half of the year: : Advanced addition
: Reading, writing, and comparing large numbers. and comparing large numbers.