Concept:
Urban Primary Health Centres are planned based on the population they serve. For slum areas, one UPHC is generally considered for about 50,000 population.
Step 1: Calculate slum population.
Total population:
\[
70,00,000
\]
Slum population:
\[
30% \times 70,00,000 = 21,00,000
\]
Step 2: Apply UPHC norm.
One UPHC is required for:
\[
50,000
\]
population.
Step 3: Calculate number of UPHCs.
\[
\frac{21,00,000}{50,000}=42
\]
Therefore, the number of UPHCs required is 42.