1. Calculate $0.25 \times 2.5 \times 2.5 \times 0.005$. $$0.25 \times 2.5 = 0.625$$ $$0.625 \times 2.5 = 1.5625$$ $$1.5625 \times 0.005 = 0.0078125$$ 2. Calculate $0.05 \times 0.1 \div 0.252 \times 100$. $$0.05 \times 0.1 = 0.005$$ $$0.005 \div 0.252 \approx 0.01984127$$ $$0.01984127 \times 100 = 1.984127$$ 3. Calculate $3.75 \times 0.01 \div 3.75 \times 0.001$. $$3.75 \times 0.01 = 0.0375$$ $$0.0375 \div 3.75 = 0.01$$ $$0.01 \times 0.001 = 0.00001$$ 4. Calculate $3.75 \times 4 \times 0.0178 \times 0.1$. $$3.75 \times 4 = 15$$ $$15 \times 0.0178 = 0.267$$ $$0.267 \times 0.1 = 0.0267$$ Final answers: 1. $0.0078125$ 2. $1.984127$ 3. $0.00001$ 4. $0.0267$