4.NOS.B.5: Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers. a. Apply estimation strategies to estimate products. b. Use strategies based on place value (e.g., partial products) to multiply. c. Use properties of operations (e.g., use doubling and halving strategy to think of 12 × 32 as 6 × 64) to multiply. d. Represent and explain the computation by connecting rectangular arrays, area models, and/or equations to the meaning of multiplication.