Find the HCF of $0.7,0.35,1.05$.

Given decimal numbers: $0.7,0.35,1.05$
First, let's equate the number of decimal places by rewriting them:

* $0.7=0.70$
* $0.35=0.35$
* $1.05=1.05$

Now, express them as numbers without decimals by multiplying by 100:
$70,35,105$

Find the Highest Common Factor (HCF) of $70,35,\text{ and }105$:

* Factors of $35=5\times 7$
* Factors of $70=2\times 5\times 7$
* Factors of $105=3\times 5\times 7$

The common prime factors are 5 and 7.

$$\text{HCF}(70,35,105)=5\times 7=35$$

Since we multiplied by 100 earlier, divide the result by 100 to get the actual HCF:

$$\text{Required HCF}=\frac{35}{100}=0.35$$