  By analyzing an electron-positron collision data sample corresponding to an
integrated luminosity of $2.93\,\rm fb^{-1}$ taken at the center-of-mass energy
of 3.773 GeV with the BESIII detector, we obtain for the first time the
absolute branching fractions for seven $D^0$ and $D^+$ hadronic decay modes and
search for the hadronic decay $D^0\to K^0_S K^0_S\pi^0$ with much improved
sensitivity. The results are ${\mathcal B}(D^0\to K^0_S\pi^0\pi^0\pi^0 )=(
7.64\pm 0.30\pm 0.29)\times 10^{-3}$, ${\mathcal B}(D^0\to
K^-\pi^+\pi^0\pi^0\pi^0 )=( 9.54\pm 0.30\pm 0.31)\times 10^{-3}$, ${\mathcal
B}(D^0\to K^0_S\pi^+\pi^-\pi^0\pi^0)=(12.66\pm 0.45\pm 0.43)\times 10^{-3}$,
${\mathcal B}(D^+\to K^0_S\pi^+\pi^0\pi^0 )=(29.04\pm 0.62\pm 0.87)\times
10^{-3}$, ${\mathcal B}(D^+\to K^0_S\pi^+\pi^+\pi^-\pi^0)=(15.28\pm 0.57\pm
0.60)\times 10^{-3}$, ${\mathcal B}(D^+\to K^0_S\pi^+\pi^0\pi^0\pi^0)=( 5.54\pm
0.44\pm 0.32)\times 10^{-3}$, ${\mathcal B}(D^+\to K^-\pi^+\pi^+\pi^0\pi^0 )=(
4.95\pm 0.26\pm 0.19)\times 10^{-3}$, ${\mathcal B}({D^0\to K^0_S K^0_S\pi^0})
< 1.57 \times 10^{-4}$ at the 90\% confidence level. Here the first
uncertainties are statistical and the second ones systematic. The newly studied
decays greatly enrich the knowledge of the $D\to \bar K\pi\pi\pi$ and $D\to
\bar K\pi\pi\pi\pi$ hadronic decays, and open a bridge to access more two-body
hadronic $D$ decays containing scalar, vector, axial and tensor mesons in the
charm sector.
