Could you wrap up 15cm by 10cm by 10cm box using a single sheet of a4 paper?

No, you cannot wrap a 15cm by 10cm by 10cm box using a single sheet of A4 paper. An A4 sheet measures 21cm by 29.7cm, which is not large enough to cover the surface area of the box completely. The surface area of the box is 2(15cm × 10cm + 10cm × 10cm + 15cm × 10cm) = 2(150cm² + 100cm² + 150cm²) = 2(400cm²) = 800cm², while an A4 sheet provides a limited area of 623.7cm².