Reference, Arithmetic 

First Mental Arithmetic provides carefully graded questions that develop children's essential mathematics skills. A downwards extension of the Schofield & Sims bestseller Mental Arithmetic, the series comprises three workbooks for Year 1 (Books 1 to 3) and three for Year 2 (Books 4 to 6). The term 'mental arithmetic' is usually associated with spoken questions. However, children using all the Schofield and Sims Mental Arithmetic materials read the questions themselves and write down their answers. A Language of Maths glossary helps to develop children's number vocabulary and three Check-ups assess children's understanding. The separate First Mental Arithmetic Answers provides answers to all questions contained in this book, plus additional resources for teachers. Book 5 includes: read and write numbers to 1000, add and subtract mentally, missing number sequences, digital clock. - from Amzon