Class 5 huh? What are your grades? If they are A+ You should read the following Mathematics books -
1.Targeting Mathematics for class - 5 by Madhubun (easy) 
2.Composite Mathematics for class -5 by R.S. Aggarwal and Vikas Aggarwal (moderate)
3. Advantage Mathematics for class 5 by Lakshmanan/Vasudevan/Rameswari (oxford)
These books will help to improve your grades a lot!
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For the record I am of class 5 as well, But I read class 6 and 7 math books
I already mastered 5
school name/ place
D.A.V. Public School KNG, Bhubaneshwar, Odisha